Today's internal combustion engines must meet ever-stricter emissions and efficiency standards demanded by consumers and government regulatory agencies. Accordingly, automotive manufacturers and suppliers expend great effort and capital in researching and developing technology to improve the operation of the internal combustion engine. Turbochargers are one area of engine development that is of particular interest.
A turbocharger uses exhaust gas energy, which would normally be wasted, to drive a turbine. The turbine is mounted to a shaft that in turn drives a compressor. The turbine converts the heat and kinetic energy of the exhaust into rotational power that drives the compressor. The objective of a turbocharger is to improve the engine's volumetric efficiency by increasing the density of the air entering the engine. The compressor draws in ambient air and compresses it into the intake manifold and ultimately the cylinders. Thus, a greater mass of air enters the cylinders on each intake stroke.
The more efficiently the turbine can convert the exhaust heat energy into rotational power and the more efficiently the compressor can push air into the engine, the more efficient the overall performance of the engine. Accordingly, it is desirable to design the turbine and compressor wheels to be as efficient as possible. However, various losses are inherent in traditional turbine and compressor designs due to turbulence and leakage.
While traditional turbocharger compressor and turbine designs have been developed with the goal of maximizing efficiency, there is still a need for further advances in compressor and turbine efficiency.